Your cam specifics and quality of rotating components determines redline. If it is unknown, I would limit your FE to 5800 until you know what you have for sure. While I agree that
oil leaks are common, you don't have to live with them and they can eventually cause bigger problems like
oil saturated clutch disks. Often, a rear main will seal itself with use, but many times leaky valve covers look like a rear main when the
oil runs down the back of the block. Identify precisely what the problem is and then determine if or how you will fix it.